The Knife is about as close to sui generis as a band gets: not only do siblings Olof Dreijer and Karin Dreijer Andersson make music that sounds like no other group currently operating, but The Knife also sounds unlike any that came before it. Shaking The Habitual, their daring, 100-minute follow-up to 2006's Silent Shout (not counting Tomorrow, In A Year, 2010's opera-styled collaboration with Mt. Sims And Planningtorock), is a superb sequel that delivers on both musical and conceptual grounds.

Let's deal with the latter first: the album title derives from French theorist Michel Foucault—the passage from which it's taken is displayed on one of the release's two posters (lyrics shown on one side and on the other comic panels bitterly decrying capitalism and material acquisition)—and the album's content explores political issues, environmental destruction, and gender studies. That Shaking The Habitual is the group's most politicized release to date might make it sound like tough going, but it isn't when The Knife's lyrics are enigmatic as opposed to didactic (e.g., “When you're full of fire / What's the object of your desire” and “Being horizontal is wonderful / Most things we love are open ended”). In titling two vignettes “Crake” and “Oryx,” Shaking The Habitual references Margaret Atwood's 2003 dystopic novel, and the brother-and-sister duo also nods to Agnetha Fältskog in calling a song “Wrap Your Arms Around Me,” the title the one-time ABBA singer gave to her 1983 solo album.

As thematically provocative as the release is, it's even more arresting on musical grounds—how could it be otherwise when its signature sound is Dreijer Andersson's animalistic howl? Hear, for example, how wildly her voice stretches out on the lines “Even in the suburbs of Rome” and “Bring the fuel to the fire” in “A Tooth For An Eye,” a mesmerizing opener powered by dizzying percussive syncopations. As head-turning as it is, it's a mere scene-setter for the album's first single, “Full of Fire,” a seething, nine-minute dynamo that finds her cryptic drawl goosed by distorted acid-techno rhythms and furious noise-making. Howling sirens merge indistinguishably into the woozy frame of “A Cherry On Top” before the setting metamorphosizes into some diseased version of Eastern-styled chant. Another left turn arrives in the form of disc one's closing “Old Dreams Waiting To Be Realized,” a nineteen-minute drone of glacial character that grew out of The Knife's desire to explore the resonant properties of an empty space, in this case an old boiler room, and “Fracking Fluid Injection,” another long-form instrumental that uses a bedspring to generate rippling wah-wahs of voices and scrapes. Also strong is disc two, which springs into action with the anthemic tribal-jazz of “Raging Lung” and Andersson's impassioned snarl (“And that's when it hurts…” ), after which jittery alien techno spritzes “Networking” with chattering electronics and beats.

Even a cursory listen to Shaking The Habitual suggests that calling The Knife an electronic group makes little sense when the categorization hardly does justice to the group's sound. Instead the album's a sprawling set that boldly transmutes genres like industrial, techno, ambient-drone, and noise into some bizarre new form. African rhythms, Asian vocalizations, and acoustic instruments (percussion and wooden flutes, for example) surface, albeit refracted through the group's distorting lens. Yes, Shaking The Habitual is arguably overlong, and it's hardly an easy listen—the sickly undertow of “Wrap Your Arms Around Me,” for instance, has little in common with anything in ABBA's pop universe—but it's also inspiring to see a now-established outfit challenging itself (reinventing itself might be more accurate) and its listeners so dramatically.